Absolute magnetic

measurements, methods and instrumentation

Domján, Á. (1)

(1) MinGeo Ltd., Budapest, Hungary


Absolute geomagnetic measurement is an

accurate determination of magnetic declination D and inclination I at

a given location and time on the Earth. These quantities are essential

to monitor the long-term baseline changes and calibration parameters

of variometers in observatories and repeat station surveys.


Methods and the instrumentation are tightly coupled to this kind of

measurement. Since all the relevant methods based on the usage of a

classical theodolite equipped with flux-gate magnetometer known as

declination inclination magnetometer (DIM). The most commonly used

method in the magnetic community is the null method. In the null

method procedure we need to find the close to zero magnetic output of

the magnetometer in a predefined sequence. Then the processing is not

more than additions subtraction and mean calculation.


In the article of (Brunke and Matzka, Numerical evaluation of magnetic

absolute measurements with arbitrarily distributed DI-fluxgate

theodolite orientations, 2018) a new method was proposed, where the

determination of D and I is a search for global minimum of the

non-linear inverse problem of the DIM instrument model. This method

more general than null method. There is no rigorous constrain about

the measurement protocol and it can process the null method data too.


DIMs have several difficulties. Measurement procedure is carried out

manually. Difficult to use DIM for I observation in equatorial region

because the telescope cannot be read in nearly vertical position even

with diagonal eyepiece. The computation of magnetic meridian is

calculated by the operator during the measurements.


To overcome this problem at MinGeo company we developed a cable-less,

digital, non-magnetic DIM instrument, known as the FluxSet Declination

Inclination Digital Station 1 (DS-1), which was designed to facilitate

the absolute magnetic measurements.


The aim of this presentation to asses the accuracy and precision of

the absolute magnetic measurements, which were measured by a reference

DIM and DS-1 instrument using null and this new proposed